Hello! Comming back to rift. Need some help :)

So its been a long time since release when I last played and id like to come back for another try as this xpac looks quite promising!

Few questions,

1. I defs want to be a Mage, but id like to do the best damage possible with no pet and nearly no DoTs if possible?
Is there such a spec? D:

2. The harbinger, is it fun to play? does alot of damage?

3. I only ever got to like level 21 before I went back to wow, now I dont wanna quit wow, just looking for something to fill the all mighty boring gap I have in wow with nothing to do. Is it hard to level in rift? Because I found it quite repetitive and boring last time, has much changed?